Apu + GPU in crossfire

[I hope this is the right subforum]

I am thinking of doing an entry level build for my brother this Christmas using the AMD A-series x4 a8-5600K as an APU and 8 gigs of 2400Mhz RAM to help things along. I was wondering is there are any AMD GPU's that will run simultaneously(crossfire?) with this APU. Just thinking ahead of time, maybe for a future birthday or something like that.

The complete parts list is here:

APU: AMD A-series X4 A8-5600K, 3.6Ghz


RAM: Kingston 8Gb 2400Mhz DDR3

HDD: Western Digital Green 2Tb

PSU: Corsair CX 500W modular

Case: Fractal Design core 1000 USB 3.0 black M-ATX

I appreciate any feedback on the general build as well, although I'd like to focus on the APU/GPU combination possibility here.

A8 supports dual graphics combinations and crossfire works only with hd6670 or hd6570